Toxicity and Efficacy of Local Ablative, Image-guided Radiotherapy in Gallium-68 Prostate-specific Membrane Antigen Targeted Positron Emission Tomography-staged, Castration-sensitive Oligometastatic Prostate Cancer: The OLI-P Phase 2 Clinical Trial

Background: Local ablative radiotherapy (aRT) of oligometastatic prostate cancer (PCa) is very promising and has become a focus of current clinical research. Objective: We hypothesize that aRT is safe and effective in gallium-68 prostate-specific membrane antigen targeted positron emission tomography (PSMA-PET)-staged oligometastatic PCa patients. Design, setting, and participants: A nonrandomized, prospective, investigator-initiated phase 2 trial recruited patients with oligometastatic PCa (five or fewer lymph node or osseous metastases) after local curative therapy, without significant comorbidity and androgen deprivation therapy (ADT), at two German centers from 2014 to 2018. Intervention: All PSMA-PET-positive metastases were treated with aRT. No systemic therapy was initiated. Outcome measurements and statistical analysis: The primary endpoint was treatment-related toxicity (grade ≥2) 24 mo after aRT. A one-sided single-sample test of proportions was planned to test whether the endpoint occurs in